Nanostructured chemicals are best exemplified by those based on low-cost Polyhedral Oligomeric Silsesquioxanes (POSS) and Polyhedral Oligomeric Silicates (POS). POSS systems contain hybrid (i.e. organic-inorganic) compositions in which the internal cage like framework is primarily comprised of inorganic silicon-oxygen bonds. The exterior of the nanostructure is covered by both reactive and nonreactive organic functionalities (R), which ensure compatibility and tailorability of the nanostructure with organic monomers and polymers. These and other properties and features of nanostructured chemicals are discussed in detail in U.S. Pat. No. 5,412,053 and U.S. Pat. No. 5,484,867, both of which are expressly incorporated herein by reference in their entirety.
Current-engineering practices produce functionalized POSS molecules in high yield but certain microelectronic, medical, and biological applications require higher-purity or chemical functionalities that are not readily or economically produced using the prior art. Prior art methods include the use of hydroxide base, anionic salts, and protic, acid catalysts in the assembly of POSS cages and their functionalization (see U.S. patent application Ser. Nos. 09/631,892 and 10/186,318, and U.S. Pat. Nos. 6,770,724; 6,660,823; 6,596,821; and 3,390,163). While these approaches are known to be generally effective, they are limited in that both protic acids and hydroxide bases can also catalyze the self-condensation of POSS individual cages into oligomerized POSS cage containing resins (FIG. 1). Such resins are not desirable in microelectronics, biological or medical applications, as their structure is molecularly imprecise. Furthermore, the dispersion of the POSS molecules and their compatibility with polymers is thermodynamically governed by the free energy of mixing equation (ΔG=ΔH−TΔS). The nature of the R group and ability of the reactive groups on the POSS cage to react or interact with polymers and surfaces greatly contributes to a favorable enthalpic (ΔH) term while the entropic term (ΔS) for POSS is highly favorable when the cage size is monoscopic and the corresponding distribution of oligomers is 1.0.
Consequently a need exists for improvement upon the prior art methods of POSS cage assembly and functionalized monomers. An improved process yielding, higher purity, and molecularly precise POSS systems is described.